Q 01/05

Where on the body is human skin at its thinnest?

A) The scalp

B) The eyelids

C) The neck

D) The inner wrists

Answer · why

B) The eyelids

The eyelids. Their skin has no layer of fat beneath it, which is why fluid makes them puff up so readily.

Q 02/05

What are the three primary layers of the skin, from outside in?

A) Dermis, epidermis, hypodermis

B) Epidermis, dermis, hypodermis

C) Cuticle, cortex, medulla

D) Stratum, cortex, subcutis

Answer · why

B) Epidermis, dermis, hypodermis

Epidermis, dermis, hypodermis. Stretch marks form in the middle one: the dermis tears when skin is stretched beyond the limits of its elasticity.

Q 03/05

Which of these does the epidermis lack entirely?

A) Melanocytes

B) Blood vessels

C) Keratinocytes

D) Nerve endings

Answer · why

B) Blood vessels

Blood vessels. The epidermis has none of its own, so its living cells depend on nutrients that diffuse up from the dermis underneath.

Q 04/05

Which cells produce the pigment that gives skin its colour?

A) Keratinocytes

B) Melanocytes

C) Merkel cells

D) Langerhans cells

Answer · why

B) Melanocytes

Melanocytes. People of every skin tone have roughly the same number of them; what differs is how much pigment each one makes.

Q 05/05

Which inherited condition leaves the body unable to turn the amino acid tyrosine into melanin?

A) Vitiligo

B) Rosacea

C) Psoriasis

D) Albinism

Answer · why

D) Albinism

Albinism. In its most severe form one enzyme, tyrosinase, doesn't work, and because it handles the very first step of the chain, no melanin gets made ...